Blood dialysis apparatus having convenient controlling unit

ABSTRACT

A hemodialysis apparatus that carries out hemodialysis treatment by controlling dialysis conditions, wherein the hemodialysis treatment is carried out under dialysis conditions determined by defining the course of said chronological target blood indication level as a target control line, measuring the blood indication level at each measurement point (controlling point) in said chronological course, calculating the dialysis conditions with the use of said measured blood indication level and the target blood indication level at the next measurement point (controlling point) of said measurement point (controlling point) in the hemodialysis apparatus carrying out hemodialysis treatment by controlling dialysis conditions with the use of blood volume (BV level) or blood volume change as an indication level (hereinafter also referred to as blood indication level), to attain the target blood indication level at the next measurement point (controlling point). This apparatus has a simple control mechanism and has little risk of misoperation or out-of-control. An operator can easily handle it and the control can be quickly and precisely carried out. Therefore, the blood volume transits appropriately during hemodialysis, which is an excellent effect.

TECHNICAL FIELD

[0001] The present invention relates to a blood treatment apparatus,especially to a hemodialysis apparatus which can control water removalconditions, for example water removal speed so as to prevent excessivewater removal and also lack of water removal in the contrary, whichoccur frequently during hemodialysis.

BACKGROUND ART

[0002] For treating patients with impaired kidney function, treatmentsby purifying blood by dialysis or filtration via semipermeable membranehave been provided conventionally. As for this apparatus, it isimportant to appropriately maintain the blood volume circulating in thepatient body, to perform safe and effective blood purification. A rapidor excessive water removal will decrease excessively patient's bloodcirculating volume, and it may cause reduction of blood pressure, shockor the like. On the contrary, if the water removal is slow, it will takea long time for blood purification, and if sufficient water removalcannot be made, there is a fear that hypertension, heart failure or thelike can occur.

[0003] Therefore, a hemodialysis apparatus performing water removal bymonitoring patient's blood condition have been developed. For example,in Japanese Laid-Open Patent Publication No. 6-83723, an estimatingapparatus which estimates the body fluid condition with a Hematocritmeter, and a controlling apparatus which controls the blood pump orultra pressure by the output of said estimating apparatus are described.Concerning this apparatus, it is convenient as the water removal iscontrolled directly according to the measured body fluid condition, buton the other hand, as the water removal is controlled directly by themeasured value, in case the measuring means is not accurate or a troublehappens, it may cause a significant problem. Therefore, in suchfeed-forward control, generally, a separate line independent from thecontrol line is disposed and a safety mechanism is loaded on said line.However, the apparatus becomes complicated when an independent line orsafety mechanism is disposed and the operation becomes difficult.Furthermore, the cost of the apparatus will rise.

[0004] Therefore, a simple apparatus as described in Japanese Laid-OpenPatent Application No. 9-149935 was also developed. In other words,while monitoring the patient's blood condition, an alarm is ringeddepending to the condition, and the water removal pump is stopped.However, this apparatus only recognizes if the water removal control isperformed under the same control condition at the time of the initiationof dialysis, by comparing with the blood concentration measured beforethe initiation of dialysis, and it is not possible to perform adequatewater removal to each patent. Furthermore, if the water removal is notperformed according to the condition, the operator has to adjust eachtime the water removal volume or substitutive fluid volume. Thus, eventhough it was safe, it was complicated and the human cost was high.Moreover, as for said apparatus, a means for measuring the bloodcondition is disposed on the line at the vein fluid side of the bloodcycle, the blood condition after having passed the blood treatmentmachine (dialyser) is measured, thus it may not reflect the patient'sdirect blood condition.

[0005] To provide a blood treatment apparatus which have solved theproblems mentioned above, that is, to provide a convenient apparatus ata low cost by making a structure wherein each patient's blood conditionis monitored, enabling to perform blood treatment adequate to eachpatient chronologically, by not imposing much burden to the operatorduring its use, and by making the construction of the blood treatmentapparatus simple, the present inventors provided a blood treatmentapparatus (Japanese Laid-Open Patent Application No. 11-22175),comprising a blood measuring means for measuring blood parameters; aworking unit for performing blood treatment; and a controlling unitcontrolling the working unit to perform blood treatment under prescribedblood treatment condition, wherein the controlling unit indicates thechange of the blood treatment to the working unit, by setting a bloodindication region determined beforehand against the patient bloodindication level obtained with said blood measuring means, according tothe chronological transition of said blood indication level in saidblood indication region. Furthermore, the present inventors haveimproved said blood treatment apparatus (Japanese Laid-Open PatentApplication No. 11-22175), and proposed a blood treatment apparatus(Japanese Laid-Open Patent Application No. 2001-540), wherein bymonitoring each patient's blood condition, the condition of hemodialysisadequate to each patient chronologically, especially the water removalspeed can be easily changed and defined. Said blood treatment apparatus(Japanese Laid-Open Patent Application No. 2001-540) is a hemodialysisapparatus comprising at least: (A) a blood measuring means for measuringblood parameter, (B) a working unit for performing blood treatment; and(C) a controlling unit for controlling the working unit to perform bloodtreatment under prescribed blood treatment condition; wherein thehemodialysis apparatus has a mechanism for controlling the water removalspeed, and the controlling unit (C) incorporates the blood indicatinglevel obtained from the patients' samples by the blood measuring means(A), monitoring if it transits or not within the defined range definedbeforehand of blood indication level (hereinafter also referred to asdefined range of blood indication level), and when said blood indicationlevel being the target to control deviates from said range definedbeforehand, the water removal speed of the working unit (B) can bechanged at a speed rate defined beforehand.

[0006] As for the hemodialysis apparatus mentioned above, it waspossible to manage surely the blood indication level at each pointduring hemodialysis treatment, but because it was necessary to definethe region of the target blood indication level at each point, theoperation was complicated. Furthermore, as the defined blood indicationlevel was designated as a range, as long as a blood indication levelexists within the defined range (even it is at the absolute edge of therange), the control mechanism of the hemodialysis apparatus would notwork. Therefore, in case the blood indication level actually measured isslightly missing the point from the target, there was a fear that thecontrol would be delayed.

DISCLOSURE OF THE INVENTION

[0007] The object of the present invention is to provide a hemodialysisapparatus having a controlling unit that controls dialysis conditions,for example the water removal speed, so that the blood volume duringhemodialysis can transit appropriately. Moreover, it is to provide ahemodialysis apparatus having improved controlling characteristicswherein the controlling means has a simple mechanism, and is easy tooperate, and on the other hand, can carry out controls speedily andprecisely.

[0008] The present invention provides a hemodialysis apparatus(hereinafter also referred to as first hemodialysis apparatus) thatcarries out hemodialysis treatment by controlling dialysis conditions,with the use of blood volume (BV level) or blood volume change as anindication level (hereinafter also referred to as blood indicationlevel), wherein the hemodialysis treatment is carried out under dialysisconditions determined by defining the chronological target course ofsaid blood indication level as a target control line, measuring theblood indication level at each measurement point (controlling point) insaid chronological course, and calculating the dialysis conditions withthe use of said measured blood indication level and the target bloodindication level at the next measurement point (controlling point) ofsaid measurement point (controlling point), to attain the target bloodindication level at the next measurement point (controlling point).Thus, the object mentioned above was solved.

[0009] Furthermore, the present inventors have found that for ahemodialysis apparatus which performs water removal by controlling theblood volume during dialysis according to said target control line assaid first hemodialysis apparatus, the blood volume change appears laterthan the change of the water removal speed, as it is shown in FIG. 3;and that in case said feed-forward control is carried out bydisregarding such phenomenon that the blood volume change appears laterthan the change of water removal speed, as said feed-forward control isa method that uses the blood indication level at the measurement point(controlling point) as the control observed level, it attains the nexttarget blood indication level according to a blood indication levelwhich is different from the blood indication level that is supposed tobe attained with the present control level, thus, big changes areobserved for the control levels necessary, for example, the controlvolume necessary to calculate the water removal speed, and therefore,the control would not be stable. The present inventors have solved theproblem caused by said control delay by considering said control delayat each control cycle in said feed-forward control.

[0010] In other words, the present inventors have improved saidfeed-forward control by calculating the forecast of dialysis conditionsnecessary to attain the next target blood indication level (blood volumechange), for example the forecast for the water removal speed, accordingto the blood indication level at the time when the time of control delayhave passed.

[0011] The improved hemodialysis apparatus is a hemodialysis apparatus(hereinafter also referred to as second hemodialysis apparatus) thatcarries out hemodialysis treatment by controlling dialysis conditions,with the use of said blood indication level as an indication level,wherein the hemodialysis apparatus is able to carrying out control(feed-forward control) being a hemodialysis treatment carried out underdialysis conditions determined by defining the chronological targetcourse of said blood indication level as a control target line,measuring the blood indication level at the control delay point at eachmeasurement point (controlling point) in said chronological course, andcalculating dialysis conditions with the use of said measured bloodindication level and the target blood indication level at the nextmeasurement point (controlling point) of said control delay point, toattain the target blood indication level at the next measurement point(controlling point).

[0012] Furthermore, the present inventors have provided a hemodialysisapparatus (hereinafter also referred to as third hemodialysis apparatus)that carries out hemodialysis treatment by controlling dialysisconditions, wherein the hemodialysis apparatus is able to carrying outcontrol (feed-forward control) being a hemodialysis treatment carriedout under dialysis conditions determined by defining the chronologicaltarget course of said blood indication level as a control target-line,calculating the dialysis conditions with the use of each bloodindication level at the two adjacent measuring points (controllingpoints) of said target control line, the water removal speed usedbetween said two measuring points (controlling points), the blood volumeat the time of the initiation of dialysis, and the target bloodindication level determined by said target control line at the nextmeasuring point (controlling point) of said two measuring points(controlling points) so that the blood indication level attains thetarget level at the next measuring level (controlling level). Thus, thepresent inventors have attained the object of the present invention.

[0013] The control of said third hemodialysis apparatus (feed-forwardcontrol) can be carried out by using the following formula (a).

BV ₀{−(%ΔBV _(n−1′)−%ΔBV _(n′))+(%ΔBV _(n′)−%ΔBV _(n+1))}+UFR _(n)×T=UFR _(n+1) ×T  (a)

[0014] (wherein BV₀ is the blood volume at the time of the initiation ofdialysis; % ΔBV_(n)′ is the blood volume change at an optional selectedmeasurement point (n); % ΔBV_(n−1)′ is the blood volume change at ameasurement point (n−1), which is the previous point of the selectedmeasurement point (n); % ΔBV_(n+1) is the blood volume change defined ata measurement point (n+1), the next measurement point to carry outfeed-forward control; T is the measurement time; UFR_(n) is the waterremoval speed at the selected measurement point (n); UFR_(n+1) is thewater removal speed defined when the control toward the working unit iscarried out, to attain the target blood indication level at ameasurement point (n+1), the next measurement point of the selectedmeasurement point (n).)

[0015] Said formula (a) is obtained as follows:

[0016] When each measurement point (controlling point) is set as 1, 2 .. . n−1, n, n+1, relational formulae as follows are obtained.

[0017] The first measurement point (controlling point) and the secondmeasurement point (controlling point) are:

BV ₀−[(100%−%ΔBV 1)−(100%−%ΔBV 2)]/T=PRR 1−UFR 1  (1)

BV ₀(−%ΔBV _(1′)+%ΔBV ₂′)/T PRR₁−UFR₁  (2)

BV ₀(−%ΔBV ₂+%ΔBV ₃)/T=PRR ₂ −UFR ₂  (3)

[0018] Here, BV₀ is BV level, which is the primary blood volume at thetime of the initiation of dialysis, % ΔBV₁′ and % ΔBV₂′ are the bloodvolume change at the first or second measurement point (controllingpoint), T is the elapsed time of dialysis. Moreover, % ΔBV₃ is the bloodvolume change determined by the target control line.

[0019] Similar relations are obtained at each of any measurement points(controlling point), (n-1) and (n), as it is shown in the followingrelational formulae.

BV ₀(−%ΔBV _(n−1′)+%ΔBV _(n′))/T=PRR _(n−1) −UFR _(n−1′)  (4)

BV ₀(−%ΔBV _(n′)+%ΔBV _(n+1′))/T=PRR 1−UFR_(n)  (5)

[0020] By subtracting said formula (3) from said formula (2), thefollowing formula (6) is obtained.

BV ₀{−(%ΔBV _(1′)−%ΔBV _(2′))−(%ΔBV _(2′)−%ΔBV ₃)}/T=PRR ₁ −PRR ₂ +UFR₂−UFR₁  (6)

[0021] When it is hypothecated there is no difference between PRR₁ andPRR₂, that is the distance between the measurement points (controllingpoint) is defined to be short so as the patient's PPR is not changedsubstantively at each measurement point (controlling point), the firstand second terms in the right side are deleted. Thus, the followingformula (7) is obtained.

BV ₀{−(%ΔBV_(1′)−%ΔBV _(2′))+(%ΔBV _(2′)−%ΔBV₃)}/T+UFR ₁ =UFR ₂  (7)

[0022] In said formula (7), % ΔBV₃ is the target level at the nextmeasurement point (controlling point), and is a level for the bloodindication level to approach by carrying out the control. UFR₂ is thewater removal speed to define so that the blod indication level of thenext measurement point (controlling point) approaches the target levelmentioned above. Moreover, BV₀ is the BV level at the time of theinitiation of dialysis (primary blood volume), % ΔBV₁′ and % ΔBV₂′ arethe blood volume change at the first or second measurement point(controlling point), and T is the elapsed time of dialysis.

[0023] Said BV₀, % ΔBV₁′, % ΔBV₂′ and T are levels already known, andUFR₁ is also known as the water removal speed used from the firstmeasurement point to the second measurement point (controlling point).Therefore, if % ΔBV₃ to be the target is specified, the water removalspeed being a dialysis condition can be calculated with the formula (7).The target BV level can be determined by the target control line, fromthe measurement point (controlling point). On the contrary, if thehemodialysis treatment is carried out with that water removal speed, theBV level at the next measurement point (controlling point) can approachthe target level, that is the target control line.

[0024] When describing the above formula for any measurement points(controlling points) (n) and (n−1), it is shown as the following formula(8), and as described above, the water removal speed to define so thatthe blood indication level approaches the target at the next point,according to the blood volume change at the two measuring points(controlling points); the water removal speed between the twomeasurement points (controlling points); the measurement level for thetime of dialysis T; and the blood volume change defined at the nextmeasurement point (controlling point) of said two measurement points(controlling point) determined according to the target control line ofsaid blood indication level.

BV ₀{−(%ΔBV _(n−1′)−%ΔBV _(n′))+(%ΔBV _(n′)−%ΔBV _(n+1))}+UFR _(n)×T=UFR _(n+1) ×T  (8)

[0025] In said formula (8), BV₀ is the blood volume at the time of theinitiation of dialysis; % ΔBV_(n)′ is the blood volume change at anoptional selected measurement point (n); % ΔBV_(n−1)′ is the bloodvolume change at the previous measurement point of an optional selectedmeasurement point; % ΔBV_(n+1) is the blood volume change defined at ameasurement point to carry out feed-forward control (next measuringpoint); T is the measured time; UFR_(n) is the water removal speed atthe selected measurement point; UFR_(n+1) is the water removal speeddefined at the next measurement point from the selected measurementpoint (n), when the control is carried out toward the working unit, toattain the target blood indication level.

[0026] However, to obtain said formulae (7) and (8), the condition that“there is no difference between the PRRs at each measurement point(controlling point)”, which was hypothecated to derive these formulae,is an assumption, and to meet this condition, it is important that thedistance between each measurement point (controlling point) (ΔT) isdefined to be short so that there is no difference between the PRRs.Moreover, as for this controlling method, errors to the control mayoccur due to errors of BV₀ at the time of the initiation of dialysis,control delay and other factors, but in the actual control, the controlis ensured by defining the water removal speed at each point(measurement point). For example, as it is shown by the graph in FIG. 2,there are substantively no problems for the errors which occur, if thedistance between each measurement point (controlling point) isshortened, and the water removal speed is defined each time.

[0027] When considering control delay mentioned above, in the control ofsaid second hemodialysis apparatus, a control carrying out hemodialysistreatment is possible under dialysis conditions calculated by definingthe chronological target course of said blood indication level as atarget control line, with the use of the blood indication level at themeasurement point (controlling point); the blood indication level at thecontrol delay point of the previous measurement point (controllingpoint) adjacent to said measurement point (controlling point); the waterremoval speed used between the measurement point (controlling point) andthe previous point adjacent to said measurement point (controllingpoint); the blood volume at the time of the initiation of dialysis; andthe target blood indication level determined by said target control lineat the next measurement point (controlling point) of said twomeasurement points (controlling point).

[0028] In the meantime, a control carried out by using a target controlline such as that described above, with the use of the blood indicationlevel at each measuring point, the next target blood indication level ofsaid each measurement point, or calculated dialysis conditions asparameters, is also called a feed-forward control.

[0029] Furthermore, the present inventors have found that said controldelay appears significantly at a point wherein said target control linechanges drastically, for example, at a point in the vicinity of thelimit of the former part of dialysis operation, performing dialysisoperation which decreases the blood volume according to the targetcontrol line A as shown in FIG. 1, and the latter part of dialysisoperation, performing dialysis operation to maintain the blood volumesubstantively stable, and that it is possible to solve said problems bythe adapting means as follows, which occur when said control delayappears significantly.

[0030] In other words, as for a method to solve said problems, a methodof changing beforehand the next target at multiple control cycles, justbefore the limit between the former control and the latter control, sothat it approaches to the condition of the target defined line of thelatter part (in the present figure, it is in a horizontal condition), ateach said control cycle. Concretely, it can be exemplified as it isshown in FIG. 4, by a method of moving horizontally the target level forone cycle respectively at each measurement point (controlling point)described above, to moderate the drastic change between the former partand the latter part. In the meantime, said number of control cycleswhich was defined beforehand, can be of any value, as long as it iswithin the range that the object of the present invention can be solved.

[0031] Moreover, as for the problem of said control delay, it was alsosolved, for example, by changing the control line that reduces thedrastic change of the target control line in the vicinity of the limitbetween the former part and the latter part of dialysis, that is, bychanging the control line that moderates the inclination of the targetcontrol line, and by carrying out the control according to said targetcontrol line that have been changed. Concretely, as shown in FIG. 5, anexample of carrying out the control by shifting the next target point ofthe multiple control cycles, in the vicinity of the limit between theformer part and the latter part of dialysis, to a more latter part ofdialysis, can be exemplified.

[0032] In the following, examples and methods for calculating the bloodvolume to be used as blood indication level or the blood volume changeand primary blood volume for the hemodialysis apparatus of the presentinvention will be explained.

[0033] 1. Blood Volume (BV) Possible for Use and Blood Volume Change

[0034] (1) BV Level

[0035] There is no specific limitation for the blood volume that can beused in the present invention, as long as it shows a blood volume thatcirculates in the patients' body, and Hematocrit level (also referred toas Ht, abbreviated) can be exemplified.

[0036] (2) ΔBV level

[0037] It refers to the change volume of said blood volume, and is thechange volume of said blood volume per time unit. It can be calculatedfrom Ht, according to the following formula.

ΔBV[BV change volume]=(Ht at the time of the initiation of dialysis/Htat the time of measurement)−1

[0038] (3) % ΔBV

[0039] It is the ratio of the blood volume change, and is shown by thefollowing formula.

%ΔBV=ΔBV (ΔBV level at the time of measurement)/BV ₀ (BV level at thetime of the initiation of dialysis)×100

[0040] (4) BV %

[0041] It is calculated by dividing the BV level at the time ofmeasurement by BV₀ which is the BV level at the time of the initiationof dialysis (also referred to as primary blood volume) and is expressedin percentage. It is shown by the following formula.

BV%=BV level at the time of measurement/BV ₀ which is BV level at thetime of the initiation of dialysis (primary blood volume)×100

[0042] 2. Definition of Other Parameters and Formulae for Calculating

[0043] (1) Definition of PRR

[0044] PRR is an abbreviation for Plasma Refilling Rate, and is definedas speed of the blood plasma refilling from the body to the bloodvessel, and shows the patient's water removal ability at each point.

[0045] (2) Formula for Calculating PRR

[0046] PPR is calculated with the following formula:

PRR _(n) −UFR _(n) =ΔBV _(n) ′/T _(n)

[0047] [wherein PRR_(n) is the Plasma Refilling Rate at an optionalselected measurement point (n), UFR_(n) is the water removal speed at anoptional selected measurement point (n), ΔBV_(n)′ is the blood volumechange at an optional selected measurement point (n), T_(n) is theelapsed time until an optional selected measurement point (n)].

[0048] Said blood volume at the time of the initiation of dialysis(primary blood volume) BV₀ which is the control parameter for thehemodialysis apparatus of the present invention, is the sum of thecirculating volume in the body and the circulating volume outside thebody, and can be calculated by the following methods for calculating (1)or (2).

[0049] (1) Method for Calculating (1)

[0050] The first method for calculating the primary blood volume (BV₀)is explained according to FIG. 6.

[0051] At the time of the initiation of dialysis, as the blood volume isnot stable, the water removal is not performed, and only the circulationoutside the body is performed. By continuing the circulation outside thebody until the blood volume stabilizes, in case the turgor pressureinside the cells is sufficiently high, and the water run over the cellsand is accumulated up to the cell stroma, it is believed that the bodyfluid (the inflow volume from the cells of FIG. 6) corresponding to theincreased blood volume circulating outside the body (space outside thebody) will move from the cells to the blood vessel. Therefore, it ispossible to obtain the primary blood volume (BV₀) for each patient,according to the following formula with the increased blood volumecirculating outside the body (space outside the body) and % ΔBV.

Primary blood volume (BV ₀)=increased blood volume circulating outsidethe body (space outside the body)/%ΔBV.

[0052] (2) Method for Calculating (2)

[0053] The first method for calculating the primary blood volume (BV₀)is explained according to FIG. 7.

[0054] By using the hemodialysis apparatus which controls dialysisconditions according to the blood indication level, only the circulationoutside the body is performed at the time of the initiation of dialysisas shown in FIG. 7, said circulation outside the body is continued untilBV level stabilizes, and when the BV level becomes stable, dialysisaccompanied by water removal is initiated, and at the same time as saiddialysis is initiated, the water removal is performed with a certaintime ΔT (within the time PRR does not change), and with a certain waterremoval speed (water removal speed A), and thus ΔBV₁, which is thechange volume of said BV level is calculated. Then, the water removal isperformed for the same time as said certain time ΔT with a differentwater removal speed (water removal speed B), and thus, ΔBV₂ which is thechange volume of said BV level, is calculated. Thus, BV₀ can becalculated by using said ΔBV₁, said ΔBV₂, water removal speed A andwater removal B.

[0055] The primary blood volume (BV₀) of each patient calculated by saidmethod, can be calculated concretely according to the following formula.

BV ₀=(water removal speed A−water removal speed B)/(−ΔBV ₁%+ΔBV ₂%)×T

[0056] Said formula can be calculated as follows:

ΔBV/ΔT=PRR−UFR

−ΔBV ₁ /ΔT+ΔBV ₂ /ΔT=water removal speed A−water removal speed B

ΔBV ₁ =ΔBV ₀[(100%−%ΔBV ₁)−(100%−%ΔBV ₁′)]

ΔBV ₂ =ΔBV ₀*%ΔBV ₂

BV ₀/ΔT(−%ΔBV₁+%ΔBV₂)=water removal speed A−water removal speed B

BV ₀/ΔT=(water removal speed A−water removal speed B)/(−%ΔBV ₁+%ΔBV ₂)

[0057] When the BV₀ level which is the primary blood volume is obtainedas mentioned above, it is preferable to calculate automatically thetarget BV % by using said BV₀ level which is the blood volume inherentto each patient and the standard blood volume (BV st) which is definedbeforehand by doctors and the like, according to the following formula(c), and to carry out control with the use of said target BV % as thecontrol object level of the hemodialysis apparatus of the presentinvention. In the meantime, the standard blood volume (BV st) is theblood volume within the range that a healthy person maintains, and it ispreferable to control the hemodialysis apparatus of the presentinvention to approach to the range of this blood volume.

Target BV%=standard blood volume (BV st)/primary blood volume (BV ₀)×100

[0058] Said standard blood volume (BV st) is a level of the blood volume(BV st) which the patient would have if healthy, defined beforehand bydoctors and the like by considering factors that might influence thehuman blood volume, for example the patient's age, sex, body height andthe like.

[0059] Hereinafter, the control line used to control the hemodialysisapparatus of the present invention will be explained.

[0060] (1) Target Control Line:

[0061] It will be explained according to FIGS. 1 and 2.

[0062] In FIG. 1, it is shown by a hatched line A in the former part ofdialysis, and by a horizontal line D in the latter part of dialysis.According to this target control line A of FIG. 1, in the former part ofdialysis, a dialysis operation, for example water removal, whichdecreases the blood volume reasonably to the body is performed, and inthe latter part of dialysis operation, a dialysis operation, for examplewater removal, which maintains the blood volume suitable to each patientaccording to the target control line D, that is, to maintain the bloodvolume substantively constant is performed. Moreover, it is shown by ahatched line A of FIG. 2. The vertical axes of FIGS. 1 and 2 show theblood indication level, for example, % ΔBV level in FIG. 2, and thehorizontal axes show the elapsed time from the initiation of dialysis.Therefore, this target control line is an indication of thechronological course or the target level of the blood indication level,and said target control line is defined before dialysis by doctors andthe like.

[0063] (2) Estimated Control Line

[0064] It will be explained according to FIGS. 1 and 2.

[0065] By using the blood indication level according to the measurementlevels such as BV, ΔBV or % ΔBV and the like at the measuring point(controlling point) and the target blood indication level shown by saidtarget control line A at the next measurement point (controlling point),the dialysis conditions (for example, the water removal speed) to attainthe target blood indication level at the next measurement point(controlling point) is calculated, and the hemodialysis treatment iscarried out under this calculated dialysis conditions (for example, thewater removal speed), to attain the next measurement point (controllingpoint). As a result, the data line B which will likely slip away fromthe target control line A, will be corrected by the dialysis conditionsnewly defined at every measurement point (controlling point), andtherefore become the estimated control line C, which transits along saidtarget control line A.

[0066] (3) Deviated Control Line

[0067] The hatched line downward sloping showed beneath the targetcontrol line A of FIG. 1 is the alarm line to function as a deviatedcontrol line E. In case dialysis operation is carried out under thecontrol of the hemodialysis apparatus of the present invention, thefeed-forward control will function, but in case the blood indicationlevel exceeds said deviated control line E, it is preferable to adapt anemergency control different from the standard control method. Forexample, as it is shown in the graph in FIG. 1, in case the data line Bshowing the transition of the data level deviates beneath the alarm lineE, the water removal means such as water removal pump and the likeshould be stopped, or if necessary, a substitutive fluid to the patientusing a substitutive fluid pump is performed by priority before carryingby the control by feed-forward. Thus, the hemodialysis apparatus of thepresent invention does not only have the function to approach the bloodindication level to the target, but in case the blood indication levelis deviated in a dangerous region, it is possible to ensure the safetyof the patient by preferentially operating the emergency control. Thedefined water removal speed is shown in the bottom half of the graph inFIG. 1.

BRIEF DESCRIPTION OF DRAWINGS

[0068]FIG. 1 is a figure explaining the embodiment of dialysisconditions (water removal speed) according to the estimated control lineof the hemodialysis apparatus of the present invention.

[0069]FIG. 2 is a figure showing the relationship of the target controlline A, data line B and estimated control line C, during the former partof the water removal operation using the hemodialysis apparatus of thepresent invention.

[0070]FIG. 3 is a figure explaining that the blood volume change(control delay) appears later than the change of the water removal speedin the hemodialysis apparatus of the present invention.

[0071]FIG. 4 explains that to solve the problem of the control delayoccurring significantly just before the vicinity of the former controlpart and the latter control part during control using the hemodialysisapparatus of the present invention, the control is carried out bychanging in advance the next target blood indication level at multiplemeasurement points (controlling points) of control cycle definedbeforehand just before the limit between the former control and lattercontrol, to approach the condition of the target definition line of thelatter part for said each control cycle.

[0072]FIG. 5 explains that to solve the problem of the control delayoccurring significantly just before the limit between the former controlpart and the latter control part during control, the control line ischanged so that the change of the target control line in the vicinity ofthe limit between the former part and the latter part of dialysis issmall, and the control for the multiple control cycles in the vicinityof the limit between the former part and the latter part of dialysis, iscarried out according to said changed control line.

[0073]FIGS. 6 and 7 are figures explaining the method for calculatingsaid primary blood volume.

[0074] Moreover, in each figures mentioned above, A is the targetcontrol line; B is the data line; C is the estimated control line; D isthe target control line; E is the alarm line; F is the urgent liquidsupply line; a, b, c, d, e, f, g, h, i, j, k, l, m, n, o and p are waterremoval speed; % ΔBV is the blood volume change measured at eachmeasurement point (controlling point); and ΔT is the measured cycle(control cycle), respectively.

BEST MODE OF CARRYING OUT THE INVENTION

[0075] In the following, embodiments of control for dialysis operationof the present invention will be explained according to FIG. 1. In thebottom half of FIG. 1, the defined water removal speed is shown.

[0076] 1. Former Part of Dialysis

[0077] (1) Start of Dialysis

[0078] When starting dialysis, as the BV level is unstable, the waterremoval is not performed at the time of the initiation of dialysis(water removal speed a=0), only the circulation outside the body isperformed, and it is waited for the time interval to pass until the BVlevel stabilizes.

[0079] (2) The Time of the Initiation of the Measurement

[0080] After the BV value is stabilized, the hemodialysis apparatus isreset and the water removal is started. Just after the initiation ofwater removal (first control cycle), as previous control cycle does notexist, and the water removal speed is impossible to predict, the waterremoval is started without carrying out the control. As for said waterremoval, BV₀ level inherent to this patient is obtained from the weightbefore dialysis, and according to said BV₀ level (primary blood volume),the water removal speed (b) is calculated to attain the target controlline at the next controlling point, and the hemodialysis is carried outwith said water removal speed. Then, the feed-forward control isinitiated and the water removal is performed with the water removalspeed ((c) to (e)).

[0081] In case the water removal speed determined as above mentioned,exceeds the maximum water removal speed prescribed beforehand, thehemodialysis is carried out with the maximum water removal speed. Forexample, among the water removal speed (a) to (i) shown in FIG. 1, thewater removal speed (d) and (h) exceed the maximum water removal speedline (the black part of the water removal speed in the figure),therefore the maximum water removal speed is used as said water removalspeed. In the meantime, when the water removal removal speed exceeds themaximum water removal speed, it is most preferable to use the maximumwater removal speed as said water removal speed, but it may be a waterremoval speed less than the maximum water removal speed. Moreover, asthe observed level of the blood indication level during dialysis atwater removal speed (f), becomes less than that of the alarm line, thewater removal speed f=0 (that is, water removal is not performed).

[0082] As a result of the termination of said water removal, the waterremoval is started again when the blood indication level exceeds thecontrol line. The primary water removal speed of control when the waterremoval is started again, is determined with the same method as for thewater removal speed (b) mentioned above, and the water removal isperformed. When the water removal volume predetermined for the formerpart of dialysis has been removed, the control of water removal for thelatter part of dialysis is started.

[0083] 2. Latter Part of Dialysis

[0084] The water removal speed is calculated to finish removing theremaining water removal volume within the target water removal time, andthe water removal is performed with said water removal speed. Whenperforming water removal with this water removal speed, the waterremoval is stopped in case the blood indication level becomes less thansaid alarm level. For example, when the water removal is performed withthe water removal speed (j), the blood indication level, for example,the blood volume change; became less than said alarm level. Therefore,the water removal at the next controlling point is stopped, and thewater removal speed (k) was set to 0. Moreover, as said water removalwas stopped, the actual blood volume change ΔBV level have beenrecovered to be above said alarm level, the water removal speed iscalculated so that the remaining water removal volume at that controltime is finished to be removed within the target water removal time(determined water removal volume), and the water removal is performedwith said determined water removal speed (1). By performing the waterremoval with said determined water removal speed (1), the actual ΔBVlevel becomes less than said alarm level again. Therefore, the waterremoval at the next controlling point is stopped and the water removalspeed (m) was set to 0.

[0085] Furthermore, as a result of termination of said water removal, asthe actual ΔBV level have been recovered to be above the control line,the water removal speed is calculated so that the remaining waterremoval volume at that control time will finish to be removed within thetarget water removal time (determined water removal volume), and thewater removal is performed with said determined water removal speed (n).However, as the water removal speed (n) of said determined water removalspeed exceeds the maximum water removal speed, the maximum water removalspeed was used as the actual water removal speed. As the target waterremoval volume was not finished removing by the end of the target waterremoval time, the water removal was performed with the maximum waterremoval speed up to the target removal volume, and the dialysis wasfinished.

[0086] In the meantime, as for dialysis operation of FIG. 1, the formerpart of the control is carried out by the feed-forward control, butaccording to the hemodialysis apparatus of the present invention, thefeed-forward control may also used for the entire control period ofdialysis operation.

INDUSTRIAL APPLICABILITY

[0087] According to the present invention, a hemodialysis apparatushaving excellent effects as follows can be obtained.

[0088] (1) The control mechanism is simple, and there is little risk ofmisoperation or out-of-control.

[0089] (2) As there is no need of difficult installation or unnecessaryoperation, the operator can easily operate without difficulty.

[0090] (3) As the control is carried out rapidly and finely, the bloodvolume can be transited fairly during the hemodialysis.

[0091] (4) By carrying out a control by considering the control delay,the control of dialysis conditions can be carried out more exactly.

1. A hemodialysis apparatus that carries out hemodialysis treatment bycontrolling dialysis conditions with the use of blood volume (BV level)or blood volume change as an indication level (hereinafter also referredto as blood indication level), wherein hemodialysis treatment is carriedout under dialysis conditions determined by defining the chronologicaltarget course of said blood indication level as a target control line,measuring the blood indication level at each measurement point(controlling point) in said chronological course, and calculating thedialysis conditions with the use of said measured blood indication leveland the target blood indication level at the next measurement point(controlling point) of said measurement point (controlling point), toattain the target blood indication level at the next measurement point(controlling point).
 2. A hemodialysis apparatus that carries outhemodialysis treatment by controlling dialysis conditions with the useof blood indication level as an indication level, wherein hemodialysistreatment is carried out under dialysis conditions determined bydefining the chronological target course of said blood indication levelas a target control line, measuring the blood indication level at acontrol delay point of each measurement point (controlling point) insaid chronological course, by calculating the dialysis conditions withthe use of said measured blood indication level and the target bloodindication level at the next measurement point (controlling point) ofsaid control delay point, to attain the target blood indication level atthe next measurement point (controlling point).
 3. A hemodialysisapparatus that carries out hemodialysis treatment by controllingdialysis conditions with the use of blood indication level as anindication level, wherein the hemodialysis treatment is carried outunder dialysis conditions determined by defining the chronologicaltarget course of said blood indication level as a target control line,calculating the dialysis conditions with the use of each bloodindication level of the two adjacent measurement points (controllingpoints) of said target control line, the water removal speed usedbetween said two measurement points (controlling points), the bloodvolume at the time of the initiation of dialysis, and the target bloodindication level determined by said target control line at the nextmeasurement point (controlling point) of said two measurement points(controlling points), so that the blood indication level becomes thetarget level at the next measuring point (controlling point).
 4. Thehemodialysis apparatus according to claim 3, wherein said control(feed-forward control) is carried out by using the following formula(a): BV ₀{−(%ΔBV _(n−1′)−%ΔBV _(n′))+(%ΔBV _(n′)−%ΔBV _(n+1))}+UFR _(n)×T=UFR _(n+1)×T  (a) (wherein BV₀ is the blood volume at the time of theinitiation of dialysis; % ΔBV_(n′) is the blood volume change at anoptional selected measurement point (n); % ΔBV_(n−1)′ is the bloodvolume change at a measurement point (n-1), a point previous to theselected measurement point (n); % ΔBV_(n+1) is the blood volume changedefined at a measurement point (n+1), a next point to carry outfeed-forward control; T is the measurement time; UFR_(n) is the waterremoval speed at a selected measurement point (n); UFR_(n+1) is thewater removal speed defined when a control toward the working unit iscarried out, to attain the target blood indication level at ameasurement point (n+1), a next point of the selected measurement point(n).)
 5. A hemodialysis apparatus that carries out hemodialysistreatment by controlling dialysis conditions with the use of bloodindication level as an indication level, wherein the hemodialysistreatment is carried out under dialysis conditions determined bydefining the chronological target course of said target blood indicationlevel as a target control line, and calculating dialysis conditions withthe use of a blood indication level at the measurement point(controlling point), a blood indication level at the control delay pointat a previous measurement point (controlling points) adjacent to saidmeasurement point (controlling point), a water removal speed usedbetween the measurement point (controlling point) and a previousmeasurement point (controlling point) adjacent to said measurement point(controlling point), a blood volume at the time of the initiation ofdialysis and a target blood indication level determined by said targetcontrol line at the next measurement point (controlling point) of saidtwo measurement points (controlling points), so that the bloodindication level becomes a target level at the next measurement point(controlling point).
 6. The dialysis apparatus according to claim 3, 4or 5, wherein the distance between each point to be measured is definedto be short so that there is no substantive difference between patients'PRR (Plasma Refilling Rate: shows the speed of blood plasma that is fromthe body to blood vessel, and is shown by the following formula (b)) ateach point, PRR _(n) −UFR _(n) =ΔBV _(n) ′/T _(n)  (b) [wherein PRR_(n)is the Plasma Refilling Rate at an optional measurement point (n),UFR_(n) is a water removal speed at an optional measurement point (n),ΔBV_(n)′ is the blood volume change at an optional measurement point(n), T_(n) is the elapsed time until an optional measurement point (n)].7. The hemodialysis apparatus according to claim 3, 4 or 5, wherein thedistance between each point to be measured is defined to be short sothat there is no substantive difference between the patient's waterremoval ability at each point.
 8. The hemodialysis apparatus accordingto claim 1, 2, 3, 4 or 5, wherein said control is carried out with theuse of a patient's inherent BV level (primary blood volume) as onecontrol factor.
 9. The hemodialysis apparatus according to claim 1, 2,3, 4 or 5, wherein said dialysis condition is water removal speed.
 10. Ahemodialysis apparatus that carries out a control according to claim 1,2, 3, 4, or 5, with the use of the blood indication level obtained by aperformance wherein water removal is not performed at the time of theinitiation of dialysis until BV level stabilizes, and then dialysis iscarried out under constant dialysis condition.
 11. A hemodialysisapparatus wherein a dialysis operation of decreasing blood volume iscarried out by a control according to claim 1, 2, 3, 4 or 5 (formercontrol) in the former part of the dialysis, and that a dialysisoperation is carried out by a control so as to maintain the blood volumesubstantively constant (latter control) in the latter part of thedialysis.
 12. The hemodialysis apparatus according to claim 11, whereinthe control is carried out by changing in advance the next target bloodindication level at a measurement point (controlling point) in themultiple control cycles, defined beforehand just before the vicinity ofa former control and latter control, to approach the target definitionline of the latter part at each control cycle.
 13. The hemodialysisapparatus according to claim 11, wherein the control is carried outaccording to a changed control line, said control line being a changewherein the control in the plural control cycles in the vicinity of thelimit of the former and latter part of dialysis is changed, so that thechange of the target control line in the vicinity of the limit betweenthe former part and latter part of dialysis is small.
 14. Thehemodialysis apparatus according to claims 1, 2, 3, 4 or 5, wherein themaximum water removal speed is defined beforehand, and if saidcalculated water removal speed exceeds said maximum water removal speed,the water removal is controlled to be performed with said maximum waterremoval speed.
 15. The hemodialysis apparatus according to claim 1, 2,3, 4 or 5, wherein a deviated control line is defined to limit thechronological change of said blood indication level within a prescribedrange, and when said blood indication level exceeds the deviated controlline, a control different from the control according to said targetcontrol line is carried out.
 16. The hemodialysis apparatus according toclaim 15, wherein said deviated control line is defined beneath saidtarget control line, and when said measured blood indication level fallbelow it, an alarm call is ring and functions as an alarm line thatstops water removal means temporarily.
 17. The hemodialysis apparatusaccording to claim 1, 2, 3, 4 or 5 wherein the target BV % is calculatedautomatically according to the following formula (c), targetBV%=standard blood volume (BV st)/primary blood volume (BV ₀)×100  (c)and the control is carried out with use of said target BV % as a controlobject blood volume of the hemodialyasis apparatus of the presentinvention.